.box3{
    height: 100px;
    width: 100px;
    background-color: pink;
}
.box4{
    height: 100px;
    width: 100px;
    background-image: url(../assets/images/bg.png);
}
.box5{
    height: 100px;
    width: 100px;
    background-image: url(../assets/images/loading.gif);
}
.box6{
    height: 100px;
    width: 100px;
    background-image: url(../assets/images/logo.png);
}